The engineering objective of a pizza box is to deliver a hot, dry and crispy pizza product during a transportation time of up to 45 minutes with a very low per unit box cost. Additional objectives include using the minimum of recycled materials and, because of the "one time use" lifetime thereof, to be made of the biodegradable material. Although the pizza pie delivery industry is large (about 1 Billion boxes delivered in the United States in 1992) and great efforts have been directed to pizza box design and development, the best boxes on the market permit product quality deterioration in about fifteen minutes from enclosing the hot pizza product.
Attempts to maintain the product in a hot condition include using leather outer insulating covers, in-car heaters, and other devices. These techniques tend to maintain temperature for several additional minutes but contribute to quality deterioration due to containment of moisture within the pizza box. But these techniques do not solve the main causes of the problem created by the conventional box design and they certainly add to the cost of the delivery system, the manner of delivery, and the labor related thereto.
It is known in the art that product heat loss through the box and moisture re-absorption by or drippings on the crust within the box are factors contributing to quality deterioration. One attempted solution includes making the box walls thicker or of multilayered or corrugated construction (see Hall U.S. Pat. No. 4,441,626), but these techniques add to costs and materials. The Hoffman U.S. Pat. No. 4,373,636 and the Holden, Jr. et al U.S. Pat. No. 3,938,726 disclose a partially insulating bottom but the supporting surfaces for the product allow much heat loss by thermal conduction. The Pizzalato U.S. Pat. No. 4,717,069, Kuchenbecker U.S. Pat. No. 4,592,914, Stern U.S. Pat. No. 4,360,118, Bressi U.S. Pat. No. 5,052,559, and the Ott et al U.S. Pat. No. 4,883,195 show several other approaches but they, too, enable much heat loss through the bottom of the box or disclose vents and foam plastics or other materials unfriendly to the environment or have added material layers or inserts. Lange et al U.S. Pat. No. 4,237,171 shows a vented box plus a multilayered construction, Mancuso U.S. Pat. No. 4,058,214 and Mills U.S. Pat. No. 3,335,846 show a vented box with a flat bottom base having a large surface area contact with a resting surface.
Other approaches include adding plastic inserts or spacers, wax paper, or other devices to try to obtain incremental benefits. See Volk U.S. Pat. No. 4,886,179 and Armeno et al U.S. Pat. No. 4,605,579. But all these types of techniques add to unit cost which are very important because of the enormous number of units delivered per year. Because all pizza boxes are used once and discarded, effects on the environment and the amount and nature of the materials used are important factors.
Today, virtually all pizza boxes on the market are square-shaped, or essentially square with four corners angled to form an augmented four-sided box, with flat tops and bottoms. See Seaman U.S. Pat. No. 4,979,667, Stease et al U.S. Pat. No. 4,993,625 and Zion U.S. Pat. No. 4,984,734, and Deiger U.S. Pat. No. 4,919,326.
The typical box today is manufactured in blank form so that it can be stacked in bundles for shipment. These blanks are stored at the respective pizza shop away from the oven location until the day of use. Personnel must fold these blanks into individual boxes and stack the completed box near the oven location.
Because of the volume of business, the box design creates serious labor and operational problems. First, time and labor are required to fold the boxes for storage near the oven location. Because the stored boxes are assembled, they require much space (1.25-1.5 inches in height, each) near the oven location. Further, when taken for use, time and labor is required to orient and open the box to permit insertion of the hot pizza product into the box bottom. Further time is required to close the box top and in some cases punch or fold vent tabs or interlocking tabs between top and bottom.
Attempts at labor saving construction include Doboze U.S. Pat. No. 4,848,543 which is made of thick (1/4") foam plastic, has a rectangular shape, and requires locking tabs of different material.